Non-target organisms: According to the latest biosafety research, spider and common green lacewing are not harmed by Bt maize.

Monarch butterfly

Plant biotechnology for pest control

The Bt concept made its first appearance in recent years, making it the first molecular approach to pest management (see: insect resistance). It has been known for almost 100 years that certain widespread soil bacteria – Bacillus thuringiensis – have a deadly, toxic effect on certain insects. The agent responsible for this is called Bt toxin, a protein produced by the toxic bacteria. When ingested by insects, the protein takes its active form, quickly destroying the insect's gut.

Preparations of Bt have been approved in Germany since 1964 for pest management. Bt is used most often for maize, potatoes, fruits, and vegetables. Bt preparations play an especially important role in organic agriculture. They consist of dried bacterial spores or the crystallised protein itself, of which there are more than one hundred identified natural variations targeting different insect groups.

Advantages of Bt preparations:

Targeted effect: The various forms of Bt toxin affect only the pests specific to the crop being treated, lowering the risk of harm to beneficial insects.

Bt toxin is harmless to mammals, including humans.

New strategies are made possible through genetic engineering. Now plants can better defend themselves against pests on their own.

Case study: Bt maize and the Monarch butterfly

The pest targeted by transgenic maize producing Bt-toxin is primarily the European corn borer (Ostrinia nubilalis). Bt maize varieties also exist designed to be effective against the western corn rootworm (Diabrotica virgifera).

Even though Bt toxin is very specific, some effects on non-target insects may be possible. Such "non-target effects" are especially likely for organisms that are closely related to the target pest. To address this risk, numerous studies have been conducted around the world on the effects of Bt crops on all kinds of insects and other small animals.

A good example is a widely publicised study conducted in the United States that suggested pollen from Bt maize harms the iconic monarch butterfly.

After an initial period of commotion, the concern subsided. The assertions of this study were only based on laboratory experiments that did not correspond to real conditions in the field. In nature, monarch butterflies do not feed on maize plants themselves, as does the European corn borer. The monarch is only affected if it feeds on wild plants dusted by Bt maize pollen. Wild plants covered with significant amounts of maize pollen are only found within a few metres of maize fields and only for a short period of the year. The effects this has on the ecology of the monarch are negligible at most.

Other studies, including research conducted in Germany and in Switzerland, have found no negative effects on non-target organisms. The organisms observed in the studies included spiders, lacewings, hover flies, beetles, and earthworms. The greatest effects on non-target organisms were always observed in fields of conventional maize, where the European corn borer is treated with chemical insecticides.

Numerous studies have addressed the potential impacts of genetically modified (GM) plants. Yet the existing evidence on the effects of GM plants is often contradictory and the quality of scientific research varies widely.

Therefore, the GRACE project will establish new tools for assessing the quality of existing studies and
will conduct comprehensive reviews to identify health, environmental and
socio-economic impacts of GM plants.